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Introduction
The instrument is a new generation of microcomputer controller for the new air-cool dry transformer. The core of it is a microprocessor combined with the most up to date digital storage technology, which makes its performance greatly improved. Compared with the traditional design of temperature controller, our new product is a more compact one with much less components, which greatly enhanced its stabilities. The temperature can be easily set by the keys on the control panel and the parameters will never be lost even after power failure. The instrument has the “black box” function which can record the temperature of the three coils of motor at the moment of power failure. This instrument has had special design both in hardware and software for anti-interference. It also has the good features of operation, installation and maintenance.
Note: All the specifications have met the requirements of JB/T7631-2005 standards.
The production line for the products has passed the certified of ISO9001.
The products have been granted as national key-new products by China Committee of Science & Technology and China Committee of Economics & Trading in 1997.
Models & Functions
The Models & their functions of BWDK series Microcomputer controller are given in the table below:
Models
Functions

BWDK-3205
Display the three coils’ temperature circularly, with outputs of Fault, Over Temp. and Power-cut, but without Fan Control Function

BWDK-3205B
In addition to the same functions as BWDK-3205, these models have outputs of three 4-20mA analog currents transmit the three analog values of temperatures.

BWDK-3205C
In addition to the same functions as BWDK-3205, these models have outputs of three 1-5V analog voltages to transmit the three analog values of temperatures.

BWDK-3205D
In addition to the same functions as BWDK-3205, these models have comm. interfaces RS-232 and they also have three digital outputs to transmit the temperatures and sensors’ states.

BWDK-3205E
In addition to the same functions as BWDK-3205, these models have comm. Interfaces RS-485 and they also have three digital outputs to transmit the temperatures and sensors’ states.

BWDK-3207
Display the three coils’ temperature circularly, with outputs of Fault, Over Temp. and Power-cut. It has the fan control functions for 1-6 fans and alarm function for any one of the power lines failure.

BWDK-3208B
In addition to the same functions as BWDK-3207, these models have outputs of three 4-20mA analog currents to transmit the three analog values of temperatures.

BWDK-3208C
In addition to the same functions as BWDK-3207, these models have outputs of three 1-5V analog voltages to transmit the three analog values of temperatures.

BWDK-3208D
In addition to the same functions as BWDK-3207, these models have comm. interfaces RS-232 and they also have three digital outputs to transmit the temperatures and sensors’ states.

BWDK-3208E
In addition to the same functions as BWDK-3207, these models have comm. interfaces RS-485 and they also have three digital outputs to transmit the temperatures and sensors’ states.

BWDK-4208E
In addition to the same functions as BWDK-3208E, this model has Temp. Display for iron core ( Phase D)

Specifications
3.1. Temp. range: -30ºC-200ºC
Measuring Precision 0.5%FS ±one bit.
Steps 0.1ºC
Power AC176V- AC242V (50 ~60Hz)
Energy Consumption 5 VA
Contacts Capacity 10A/220VAC
Sensors 3 Pt100 resistors & 3 PTC resistors
Weight Less than 3Kg
Dimension 260×200×80mm

Function Descriptions
Display between the three coils’ temperatures and the highest temperature.
According to the preset temp to control fan’s switch so that to ensure dry transformer works well in normal temp. When any one of the three coil’s temp is over preset value, or under the operator’s intervention, the cooling fan will work and the “Fan” LED on the panel will be on.
The transformer can be connected with 1-6 fans. When fans are on, the “Fan” LED on the panel will become “Green”; and when fans are malfunctioned, the “Fan” LED on the panel will become “Red” and the alarming buzz will be on. If the number of connected fans is less than 6, the LED for the unconnected fans will not be on
Over temp Alarm function. When one coil’s temp is exceeded, it will output an alarm signal and the “Over-Temp” LED on the control panel will be on. At the same time, the Over-Temp output terminals will send a signal to the remote control unit to activate alarming signals.
Auto-Power-Cut function. When the highest coil temp has increased the preset limit for 6 seconds, it will send an alarm signal and the “Power-Cut” LED on the panel will be on. At the same time, Power Cut output terminals will send signals to cutoff the power in order to protect the transformer.
If the PTC sensor has been used, the Auto-Power-Cut output terminals will not activate unless both kinds of sensors, the PT100 and PTC, have detected the coils’ temperature meets the preset limit, thus increasing the reliability of Power-Cut function.
The “Fault” LED and buzzer will be on if any one of the three sensors has malfunctioned. Fault signals will be sent out from the Fault output terminals.
The colors of LED represent the related faults: Yellow=Line A, Green=Line B and Red=Line C. When all sensors work fine, no LED will be on.
The display of different codes has been used to present the working states of sensors. H means the sensor has been disconnected and L means short cut.
If one or two sensors malfunctioned, the fan will be only controlled by the working one. If all of the three sensors malfunctioned, the fans will be on immediately.
The fan on & off temp., over-temp temp, power cut temp, timer of fan on & off, the communication address and the connected fans number can all be set by panel keys. The preset data will never be lost even after power is cutoff.
The fan can be on & off through human intervention. This function can also be used to test the fans.
There is a timer to control the fan on and off, which can be set through panel keys. The range of timer is from 0 to 255 hours (if 0 is set, this function is canceled). When the preset time is up, the fans will be on for one minute and then stop. The default value of the timer is 24 hours.
The instrument is equipped with a “black box” which keeps the temp. of power off in memory for future inquiry. The recorded data will not be changed if the power off temp. is below 80ºC.
Recording the highest temperature of each phase since power on, to prepare query。
Simulation temp check function：In Simulation temp check status, the controller will control according to the simulation temp set by pressing panel keys.